In the prior art, the concentration of carbon dioxide in a carbonated liquid beverage is typically measured by obtaining a sealed container such as a can or a bottle filled with the carbonated liquid. The carbonated liquid comes to equilibrium with the gas phase above the liquid and the equilibrium pressure is directly related to the carbon dioxide content of the liquid and the liquid temperature. The carbon dioxide content of the beverage can be determined by measuring the temperature and pressure in the container and applying a mathematical relationship which is dependent on the temperature and pressure of the container, including its contents and other chemical properties of the beverage. This mathematical relationship has been determined empirically. However, the method just described is not applicable in a typical high speed bottling or canning line which runs at hundreds of cans a minute. A procedure in which a container is removed and then measured would allow many containers to be filled before an adjustment could be made for the carbonation level of the beverage.
The carbonated beverage industry presently utilizes product lines which are maintained at near freezing in order to better control the level of carbon dioxide in the lines. Because of the expense of cooling the lines, the trend has been to go to room temperature. However, maintaining a constant level of carbonization in the lines at room temperature with presently available instrumentations and procedures is not without any problems. Several factors contribute to the problems. For example, at higher product temperature, the carbon dioxide pressure is necessarily increased. Also, the carbonization level between one type of product, such as a cola is only slightly different but of critical importance from another type of product, such as an orange drink, thus making control even more difficult.
The present invention provides a solution to the above-mentioned problems.